Re: [Boston.pm] Timing out a long process and retaining the output

[Mike Williams]

Ben Boulanger wrote:
Code is below:


 make this local $SIG{ALRM} = sub { print "$test\n"; die 'died in 
eval\n'; };
make this local and put it inside the eval to avoid conflict with signal 
handlers already in place (if the timeout occurs within a system call)
see: perldoc -f alarm for more details

eval {
           local $SIG{ALRM = sub { $timeout++; die; }
it is not safe to make any system calls within a signal handler
imagine what might happen if your code was in the middle of executing a 
print statement when the signal occurred...
it is best to just set a flag then check the flag after the eval
       while (<CMD>) {
               $test .= $_;
               #$x++;
               #if ($x = $total) {
               #       close(CMD);
               #}
       }
       print "$test";
       alarm(10);
};
if ($timeout) {
    print "eval timed out\n";
}
Here ia a hacked verion of the code you posted:
#!/usr/bin/perl -w
use strict;
use IO::Socket;
STDOUT->autoflush();
my ($test, $x, $timeout);
print scalar(localtime()), "\n";
eval {
        local $SIG{ALRM} = sub { $timeout++; die;};
        open(CMD, "<blah") or die "could not open blah $!";
        $test = "test.";
        alarm(10);
        while (<CMD>) {
                chomp;
                $test .= ' ' . $_;
                $x++;
                for (my $i = 0; $i < 1_000_000; $i++) { ; }
        }
        print "$test $x\n";
};
if ($timeout) {
    print "timeout error on eval x => $x ($@)";
    print scalar(localtime()), "\n";
}
[EMAIL PROTECTED] hacking]$ ./pmalarm.pl
Mon Sep 20 15:52:42 2004
timeout error on eval x => 42 (Died at ./pmalarm.pl line 12, <CMD> line 42.
)Mon Sep 20 15:52:52 2004
[EMAIL PROTECTED] hacking]$
Hope this helps,
Mike
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